Sergey V. Kharlamov

Two-wave structure of liquid film and wave interrelation in annular gas-liquid flow with and without entrainment

The wavy structure of liquid film in downward annular gas-liquid flow with and without liquid entrainment is examined for a wide range of gas velocities using high-speed laser-induced fluorescence technique. It is shown that the wavy structure is always represented by two types of waves, long-lived and short-lived waves with the latter always generated at the back slopes of the long-lived waves. Main regularities of short-lived wave generation and evolution are also described.

Antimicrobial activity of pyrimidinophanes with thiocytosine and uracil moieties.

Reactions of pyrimidinophanes with two 6-methylthiocytosine and one 5(6)-alkyluracil moieties bridged with each other by polymethylene spacers with methyl or nonyl p-toluenesulfonate, p-toluenesulfonic acid, methanesulfonate and trifluorosulfonate afforded amphiphilic macrocyclic bis-p-toluene-, methane- and trifluorosulfonates. Despite the presence of several reaction centers in the initial pyrimidinophane molecules, protonation and methylation occurred only at the N(1) atom (with quaternization) of the 6-methylthiocytosine moieties. The bacteriostatic and fungistatic activity of the products was estimated. Macrocyclic tosylates exhibit a remarkable selectivity towards Staphylococcus aureus, with MIC values comparable with a reference drug. Bacteriostatic activity of the amphiphilic pyrimidinophanes depends on the size of the macrocycles, and the highest activity corresponds to definite lengths of polymethylene bridges. Besides, the antimicrobial activity of the screened pyrimidine derivatives depends on their topology. While macrocyclic tosylates are more active against bacteria than against fungi, acyclic tosylate with the same structural fragments shows a dramatical decrease of MIC towards mold and yeast with respect to the corresponding macrocycle. It is found that macrocyclic and acyclic tosylates in high dilutions decrease the extracellular lipase activity.

GIAO DFT 13C/15N chemical shifts in regioisomeric structure determination of fused pyrazoles.

The combined use of two‐dimensional NMR correlation experiments and gauge including atomic orbital density functional theory in 13C NMR chemical shift (CS) calculations allowed reliable and simple structural determination of regioisomeric heterocyclic systems that originate from the reactions of acylquinolinones with substituted hydrazines. Moreover, the results of differential analysis between the calculated 15N NMR CSs for hypothetical structures and the experimental data of the title azaheterocyclic systems were even more advantageous with respect to 13C because there was no need for correlational analysis: structures of the regioisomeric compounds could be determined just by direct comparison. Copyright

Self-assembly of an aminoalkylated resorcinarene in aqueous media: host–guest properties

A new water-soluble resorcinarene, with a negatively-charged lower rim and a positively-charged upper rim self-assembles into supramolecular oligomers to bind 1,5-diaminonaphthalene in water.

Controlling the Size and Morphology of Supramolecular Assemblies of Viologen–Resorcin[4]arene Cavitands

A novel class of self-assembling nanoparticles is formed with viologen-resorcin[4]arene cavitands; the association model is strongly controlled by their hydrophobicity. Interestingly, the cavitand assemblies are designed through click chemistry to form self-assembled noncovalently connected aggregates through counterion displacement. The iodide and benzoate ions are utilized as strongly polarizable counterions to induce cavitand self-assembly. The counterion-mediated decrease in hydrophilicity of the viologen-resorcin[4]arenes is the underlying trigger to induce particle formation. These particles can be used as nanocontainers and find their applications in delivery systems.

Tunable biomimetic systems based on a novel amphiphilic pyrimidinophane and a helper nonionic surfactant

Tunable nanosystems based on a novel water insoluble pyrimidinic amphiphile are designed. pH dependent aggregates composed of protonated pyrimidinophane 1 are formed at pH<4, which undergo reversible transition to precipitate at neutral and basic conditions. The approach assuming the application of a helper nonionic surfactant Triton-X-100 (TX-100) is used in this work. Different models of a self-assembly were found depending on the molar ratio of components and solution pH. In the equimolar 1-TX-100 solution, mixed assemblies contributed by aggregated molecules of both TX-100 and cationic form of 1 are formed in acidic conditions. Upon alkalization, deprotonated pyrimidinophane molecules shift toward the micellar core. The assemblies undergo reversible precipitation after 4-5h, while the excess of TX-100 leads to the formation of highly stable mixed aggregates. The acidification-alkalization cycles followed by the aggregation/precipitation and the re-charging of aggregates can be multiply repeated. Surprisingly, stable mixed aggregates are also formed under the excess of pyrimidinophane in both the acidic and alkaline conditions, but at a certain component ratio. They are characterized by the highest micellization degree among all the systems studied. The low concentration threshold of these assemblies in alkali solution is probably due to their nonionic character.

pH-controlled photoinduced electron transfer in the [(Mo6Cl8)L6]-calix[4]resorcine-dimethylviologen system.

A pH-controlled photoinduced electron transfer in the supramolecular system [(Mo(6)Cl(8))L(6)]-calix[4]resorcine-dimethylviologen is reported.

Aggregation in a mixture of cetyltrimethylammonium bromide and polyoxyethylene 600 monolaurate solutions

Micellization in the cetyltrimethylammonium bromide (CTAB)-polyoxyethylene 600 monolaurate (PL)-chloroform system is studied with dielcometric titration, NMR self-diffusion (2D DOSY), 13C NMR spectroscopy, and light scattering methods. The formation of mixed aggregates of surfactants is established. It is shown that CTAB and PL polar moieties interact in the inverse micelle core in the vicinity of PL carbonyl group.